Potatoes can be a staple of home grown produce. But they do tend to take up a lot of space. For this reason, you may not have considered growing potatoes in your polytunnel. But potatoes can be an excellent choice for polytunnel growing. Not only will a polytunnel help to protect your potato plants from inclement weather conditions, a polytunnel can also allow you to harvest first early potatoes much earlier than would otherwise be possible – or to harvest a second crop of new potatoes much later in the year. Here are some tips to help you gain a good yield from your polytunnel-grown potatoes:
While it is not absolutely necessary, chitting seed potatoes before you plant them can help to speed up the process and will allow you to enjoy first early potatoes earlier than ever before. To chit potatoes (allow green shoots to form), simply place your seed potatoes in a cool, light place. Ideally, shoots should be around one centimetre in length before you plant them. Choose proper seed potatoes rather than just chitting store-bought potatoes, as these are less likely to succumb to disease or other problems later on.
Potatoes are hungry and thirsty plants. Preparing your growing areas well before planting your potatoes can help you to make sure you get a good harvest of potatoes from your polytunnel. If sowing in the soil, or a raised bed, dig a trench in which to place your potatoes. In the base of the trench, it can be helpful to place a good amount of compost/ organic matter to feed your plants. This will help to ensure your potato plants have what they need as they begin to grow.
When deciding whether or not you have space for potatoes in your polytunnel, remember that you may not need to grow potatoes directly in the soil. Large containers or grow bags can also be used to grow potatoes under cover, and these could be a good way to make use of all the space in your polytunnel. In order to get the maximum yield possible, it is important not to be tempted to place too many seed potatoes in each container. Err on the side of caution and stick to two potatoes per grow bag (or recycled compost bag, for example).
As potato plants in your polytunnel stick their heads above the soil, it is important to make sure that they do not succumb to damage due to late frosts, which can strike well into the spring, especially in more northern areas of the UK. To protect the tender tips of potato plants from a late frost, you can mulch around them with straw or other organic material, or use cloches made from plastic bottles, scrap fabric or horticultural fleece.
As potato plants grow, you should earth up around the plants, or cover the growing stems to encourage further tuber formation with a thick organic mulch. Seaweed, bracken or home-made compost can all be excellent choices for this purpose.